Understanding CAN CGSB 4.2 No. 32.1-98 (2013): Standard for Resistance to Slippage of Yarns in Woven Fabrics

CAN CGSB 4.2 No. 32.1-98 (2013) is a Canadian national standard developed by the Canadian General Standards Board (CGSB) that specifies a test method for determining the resistance of yarns to slippage at a seam in woven fabrics. Often referred to as the seam slippage test, this standard is essential for evaluating the dimensional stability and structural integrity of woven textiles under tensile stress. The latest reaffirmation (2013) confirms its continued relevance in the textile and apparel industry.

Scope and Application

This standard outlines two principal procedures for measuring yarn slippage in woven fabrics:

• Procedure A — Determination of the force required to produce a specified seam opening (e.g., 3 mm or 6 mm).
• Procedure B — Determination of the seam opening after applying a specified force (e.g., 100 N or 200 N).

The method is applicable to woven fabrics, including those with wales and courses, but is not intended for non-woven or knitted structures unless specifically agreed upon by the contracting parties. The test is performed in both warp (lengthwise) and weft (crosswise) directions to evaluate the fabric’s resistance to seam slippage, which directly affects garment performance—particularly in areas subject to stress such as armholes, seat seams, and pocket corners.

Technical Requirements and Test Procedures

Apparatus and Conditioning

The test requires a constant-rate-of-extension (CRE) tensile testing machine equipped with a load cell capable of measuring forces up to at least 500 N with an accuracy of ±1%. Specimens must be conditioned in a standard atmosphere of 20 ± 2°C and 65 ± 4% relative humidity for a minimum of 24 hours prior to testing, in accordance with CAN/CGSB 4.2 No. 2 (or ISO 139).

Specimen Preparation

Test specimens are cut to 100 mm × 200 mm, with the longer dimension parallel to the direction of testing. A seam is sewn across the center of the specimen using a plain seam construction with specified thread (e.g., 100% polyester spun thread, ticketed size 24/3) and a stitch length of 10 stitches per 25 mm. Seam allowance is 10 mm. A minimum of five warp and five weft specimens are required for each test direction.

Test Conditions

Procedure

Each specimen is mounted in the tensile tester with the seam centered between the clamps. The jaw separation is set to 75 mm. The specimen is pulled at a constant rate of 100 mm/min until a predetermined seam opening (e.g., 3 mm or 6 mm) is reached, and the corresponding force is recorded. Alternatively, for Procedure B, the force is applied up to a specified level, and the seam opening is measured. The mean force (or opening) for each direction is reported.

Implementation Highlights

Successful implementation of CAN CGSB 4.2 No. 32.1-98 (2013) requires attention to several practical details:

• Seam construction: The thread type, tension, and needle size must be standardized between operators. Any variation may lead to inconsistent seam formation and unreliable test results.
• Specimen orientation: Ensure that the direction of testing is clearly marked (warp or weft). For fabrics with directional designs, the specimen should be taken from areas free of intentional distortions.
• Curved fabrics: For garments with curved seams, the standard advises using the procedure that best simulates the end-use configuration, though the flat specimen method remains the primary reference.
• Alternative opening criteria: For heavy-duty fabrics (e.g., denim, upholstery), a 6 mm opening is often used instead of 3 mm to obtain more meaningful results.

Compliance Notes and Quality Assurance

Compliance with CAN CGSB 4.2 No. 32.1-98 (2013) is often required for Canadian government procurement and for textile products sold in Canada. Key compliance points include:

• Precision: Interlaboratory studies cited in the standard indicate a coefficient of variation between 5% and 12% for seam slippage force measurements. Laboratories should participate in round-robin tests to ensure reproducibility.
• Seasonal fluctuations: Ambient humidity changes can affect fabric dimensional stability; testing must always be performed under standard atmospheric conditions to obtain comparable results.
• Reference standards: CAN CGSB 4.2 No. 32.1 is technically equivalent to ISO 13936-1 and closely aligned with ASTM D1683. However, differences in seam allowance and stitch density may yield slightly different absolute values.

For quality control purposes, it is recommended to establish internal action limits (e.g., ±1.5 times the standard deviation of the historical mean) to detect shifts in fabric behavior due to changes in yarn tension, weaving variables, or finishing treatments.

Frequently Asked Questions